System and method for increasing cellular site capacity

ABSTRACT

Systems and methods for providing wireless services to a plurality of user equipments (UEs) is disclosed. A device can have a plurality of antennas, each having two or more beams. The plurality of antennas can divide the coverage area into sectors based on the two or more beams of each antenna, and each beam can overlap with a beam in an adjacent sector. The device can transmit a reference signal in each sector via the associated beam, received one or more measurement reports from UEs within each sector, indicating a received quality of at least one reference signal. The device can assign a sector edge UE to a sector based on the measurement report.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Patent Application62/327,815, filed Apr. 26, 2016, and entitled, “SYSTEM AND METHOD FORINCREASING CELLULAR CAPACITY,” the contents of which are herebyincorporated by reference in their entirety.

BACKGROUND Technical Field

This disclosure generally relates to wireless communication. Morespecifically, this disclosure relates to increasing wireless capacity ofcellular systems. This disclosure relates to multi-cell,multi-subscriber wireless systems and various methods for interferencemitigation to increase the capacity of a cell site and enhance thethroughput of cell edge users.

Related Art

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, video, and so on.These systems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE)/LTE-Advanced systems andorthogonal frequency division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal can communicate with at least one base station (BS) viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations. The base stations can alsobe referred to as node B's or evolved node B's (eNB). The eNB or BS canalso be termed an access point (AP).

A wireless communication network can include a number of base stationsthat can support communication for a number of wireless devices orwireless terminals. A wireless device can be a user equipment (UE), forexample, in a LTE environment. A UE is a device that can providewireless services to a user. Some examples of UEs include cellularphones, smart phones, personal digital assistants (PDAs), wirelessmodems, handheld devices, tablets, phablets, laptop computers, netbooks,smartbooks, and ultrabooks, among other examples.

SUMMARY

In general, this disclosure describes systems and methods related to theinterference mitigation in base stations having multi-beam directionalantennas. The systems, methods and devices of this disclosure each haveseveral innovative aspects, no single one of which is solely responsiblefor the desirable attributes disclosed herein.

One aspect of the disclosure provides a device for wirelesscommunications having a coverage area for providing wireless services toa plurality of user equipments (UEs). The device can have a plurality ofantennas. Each antenna of the plurality of antennas can have two or morebeams. The plurality of antennas can divide the coverage area intosectors based on the two or more beams of each antenna. Each sector canhave an associated beam, wherein adjacent beams overlap in an overlaparea. The sectors can be arranged radially about the device. The devicecan have one or more transceivers coupled to the plurality of antennas.The one or more transceivers can transmit a reference signal in eachsector via the associated beam. The one or more transceivers can receiveone or more measurement reports from the plurality of UEs within eachsector. The one or more measurement reports can indicate receivedquality of at least one reference signal. The device can have one ormore processors in communication with the one or more transceivers. Theone or more processors can assign a sector edge UE to a sector based onthe measurement report, the sector edge UE being located at a sectoredge of one or more of the sectors.

Another aspect of the disclosure provides a method for reducinginter-sector interference for a base station having one or moremulti-beam antennas each. The one or more multi-beam antennas can havetwo or more beams and the base station can have a coverage area. Themethod can include dividing the coverage area into sectors based on oneor more beams associated with each antenna. Each beam can be associatedwith a sector. Each sector can have a sector edge bordering an adjacentsector. The sectors can be arranged radially around the base station.The method can include transmitting a reference signal via each beam toone or more user equipments (UEs) in each sector, each sector having areference signal. The method can include receiving, at a transceivercoupled to the multi-beam antenna, one or more measurement reports fromthe plurality of UEs, the one or more measurement reports indicatingreceive quality of at least one reference signal. The method can includedetermining that at least one UE of the plurality of UEs is a sectoredge UE located at a sector edge of one or more of the sectors, based onthe one or more measurement reports. The method can include assigning,based on the determining, the sector edge UE to a sector having a higherreceive quality.

Another aspect of the disclosure provides a method for improvinginterference mitigation in a coverage area of a base station. Thecoverage area can have a plurality of single-beam antennas each having aform factor. The method can include replacing one or more single beamantennas of the plurality of single-beam antennas with a multi-beamantenna to form an improved antenna array. The multi-beam antenna canhave two or more beams and the form factor of the plurality of singlebeam antennas. The method can include dividing the coverage area intosectors based on the number of beams of the coverage area after thereplacing, each sector being associated with a single beam. The methodcan include transmitting a reference signal to one or more userequipments (UEs) in each sector, each sector having a reference signaland a sector edge proximate an adjacent sector. The method can includereceiving, at a transceiver coupled to the improved antenna array, oneor more measurement reports from a UE of the one or more UEs within eachsector, the one or more measurement reports indicating a receive qualityof the reference signal. The method can include determining that the UEis a sector edge UE located proximate two adjacent sectors based on themeasurement report. The method can include assigning, based on thedetermining, the UE to one sector of the two adjacent sectors having ahigher receive quality.

Other features and advantages of the present disclosure should beapparent from the following description which illustrates, by way ofexample, aspects of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of embodiments of the present disclosure, both as to theirstructure and operation, may be gleaned in part by study of theaccompanying drawings, in which like reference numerals refer to likeparts, and in which:

FIG. 1 is a graphical representation of a wireless communication system;

FIG. 2 is a graphical representation of an embodiment of the system ofFIG. 1;

FIG. 3 is a graphical representation of an embodiment of a system usingfrequency reuse factors according to the system of FIG. 2;

FIG. 4 is a graphical representation of an embodiment of the cell ofFIG. 2 using dual beam antennas;

FIG. 5 is a plot diagram of antenna coverage in the embodiment of FIG.2;

FIG. 6 is a plot diagram of antenna coverage in the embodiment of FIG.4;

FIG. 7 is a graphical representation of a four sector cell;

FIG. 8 is a graphical representation of an embodiment of the cell ofFIG. 7 using dual beam directional antennas;

FIG. 9 is a graphical representation of a coverage area of anotherembodiment of the cell of FIG. 2;

FIG. 10 is a graphical representation of a coverage area of anotherembodiment of the cell of FIG. 9;

FIG. 11 is a graphical depiction of another embodiment of the cell ofFIG. 4;

FIG. 12 is a flowchart of an embodiment of a method for intra sitecoordinated multi point communications;

FIG. 13 is a flowchart of an embodiment of a method for assigning a UEto a serving sector of an eNB; and

FIG. 14 is a functional block diagram of a device for use in the systemof FIG. 1 and the cells of FIG. 4 through FIG. 11 and the methods ofFIG. 12 and FIG. 13.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theaccompanying drawings, is intended as a description of variousembodiments and is not intended to represent the only embodiments inwhich the disclosure may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof the embodiments. However, it will be apparent to those skilled in theart that the disclosure may be practiced without these specific details.In some instances, well-known structures and components are shown insimplified form for brevity of description.

This disclosure describes a method and apparatus for increasing thecapacity of a cell site and enhancing the throughput of cell edge users.The disclosed systems and methods can include replacement of existingsingle beam antennas with a dual beam (or poly beam) antenna ofequivalent form factor or size, shape, and weight. Each beam of the dualbeam antenna can have a narrower beam width roughly equal to half thebeam width of the antenna it replaces. When multi-beam antennas areused, each beam of the multi-beam antenna can have a narrower beam widthroughly equal to 1/K the beam width of the antenna it replaces, where Kis the number of beams in a multi-beam antenna. By connecting an eNBradio and modem to each of the beams, the device of this disclosure canincrease the tonnage delivering capacity (measured in Gigabytes (GB)) ofa site, without incurring the cost of erecting a new site or spectrumacquisition. In some cases the tonnage capacity and be increased by twoor more times.

Some advantages can be achieved using a dual beam (or multi-beam)antennas with the same form factor as an existing single beam antenna.For example, if only mere replacement of the antennas is required, noapproval from municipalities may be required when replacing an antennawith a similar size antenna. Additionally, wind loading of the new (dualor multi-beam) antenna would be the same as the wind loading of the old(single beam) antenna. Therefore, it would be easier to replace the oldwith the new. Moreover, if the weight of the new (dual or multi-beam)antenna is the same, then site surveys or engineering studies can beaccelerated or eliminated, thereby saving time and cost and speedingdeployment and upgrades.

The disclosure further provides a method and apparatus to enhance thecoordination between adjacent sectors of one or more BSs, so that thethroughput, measured in Megabits per second (Mbps), delivered to UEs atthe edge of a cell are equivalent to that of UEs at the center of acell. This can be accomplished by measuring different physical cellidentities (PCIs) and relative signal strength to determine an optimumserving cell or serving sector. This can also be accomplished by mappingUEs using signal strength or their geographic positions and allocatingeach UE to the optimum serving sector/cell based on their relativelocation and based on the relative interference experienced from twoadjacent sectors. The invention further describes the means to classifyUEs as “center cell” UEs for which no coordination is necessary, and“cell edge” UEs for which coordination may be needed.

Some networks can broadcast synchronization signals from the BS (e.g.,an eNB) to the UE in the downlink direction. The synchronization signal,also known as Cell Reference Signal (CRS) or simply Reference Signals(RS) can be used by UEs to identify their respective serving cells(e.g., BS). The synchronization signals are made up of PrimarySynchronization Signals (PSS) and Secondary Synchronization Signals(SSS), and when combined make up the PCI of a cell

The systems and methods described herein may be used for variouswireless communication networks such as CDMA, TDMA, FDMA, OFDMA,SC-FDMA, LTE, LTE-Advanced and other networks. The terms “network” and“system” are often used interchangeably. A CDMA network may implement aradio technology such as Universal Terrestrial Radio Access (UTRA),CDMA2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants ofCDMA. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. A TDMAnetwork may implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA network may implement a radiotechnology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSMare described in documents from an organization named “3rd GenerationPartnership Project” (3GPP). CDMA 2000 and UMB are described indocuments from an organization named “3rd Generation Partnership Project2” (3GPP2). The systems and methods described herein may be used for thewireless networks and radio technologies mentioned above as well asother wireless networks and radio technologies. For clarity, certainaspects of the techniques are described below for LTE, and LTEterminology is used in much of the description below. This is notintended to be limiting as the principles, improvements, and advantagesof this disclosure may be applicable in other communication protocols.

Evolved NodeBs (eNBs) (e.g., a BS) of a network may be pooled togetheras virtual cells so that they can be treated as one large resource bynetwork managers and users. Each virtual cell may include a group ofphysical cells that may jointly serve a UE. A virtual cell may include aRemote Radio Unit (RRU) with a centralized Baseband Unit (BBU) thatcontrols the RRUs. In some cases the virtual cell may be made up of aset of All-In-One eNB's which combine an RRU and a BBU but areassociated with one another through a controller (see below) whichperforms the coordination between the individual all-in-one eN B's.

FIG. 1 is a graphical representation of a wireless communication system.A wireless communication system (system) 100 can be, for example, acellular network. In some embodiments, the system 100 can be an LTEnetwork.

The system 100 can include a number of evolved NodeBs (eNBs) 110 andvarious other network entities. FIG. 1 depicts eNBs 110 a, 110 b, 110 c,that can be referred to collectively as eNBs 110. The eNBs 110 can be abase station (BS) or access point (AP) that communicates with one ormore UEs 120. The eNBs 110 can also be Node B's, which are anotherexample of a station that communicates with the UEs 120. UEs 120 a, 120b, 120 c, 120 d, 120 e, 120 f are shown and can be collectively referredto as UEs 120. The UEs 120 can also be referred to a mobile terminals,user terminals, and handsets, and can refer to a wireless-enabled mobilecommunication device.

Each of the eNBs 110 can provide communication coverage for a particulargeographic area. In 3GPP, the term “cell” can refer to a coverage areaof an eNB 110 and/or an eNB subsystem serving this coverage area,depending on the context in which the term is used. In some embodiments,the system 100 can have one or more cells 102. Three cells 102 are shownas cell 102 a, cell 102 b, and cell 102 c. Each of the cells can have arespective coverage area 104 to provide wireless services to the UEs 120within. In general, the cell 102 refers to the area served by the eNB110. The coverage area 104 can be a designated area surrounding the eNB110 in which a usable signal is available to the UEs 120. Additionally,the cells 102 providing service to various UEs 120 within the coverageareas 104 can be “serving cells.”

The system 100 can have a number of eNBs 110 that can supportcommunication for a number of the UEs 120. For example, the UE 120 a cancommunicate with the eNB 110 a via the downlink and uplink. The downlink(or forward link) refers to the communication link from the eNB 110 a tothe UE 120 a, and the uplink (or reverse link) refers to thecommunication link from the UE 120 a to the eNB 110 a.

The wireless network 100 may be a heterogeneous network that includeseNBs 110 of different types, such as for example, macro eNodeBs, picoeNodeBs, femto eNodeBs, relays, etc. These different types of eNBs 110can have different transmit power levels, different coverage areas 104,and different impact on interference in the wireless network 100. Forexample, macro eNBs 110 may have a high transmit power level (e.g., 20Watts) whereas pico cells, femto cells, and relays may have a lowertransmit power level (e.g., 1 Watt).

The system 100 can support synchronous or asynchronous operation. Forsynchronous operation, the eNBs 110 may have similar frame timing, andtransmissions from different eNBs 110 can be approximately aligned intime. For asynchronous operation, the eNBs 110 can have different frametiming, and transmissions from those different eNBs 110 may not bealigned in time.

A controller 130, depicted as a functional block, can be capable ofcommunication with, or otherwise coupled to, a set of the eNBs 110 andprovide coordination and control for these eNBs 110. The controller 130can communicate with the eNBs 110 via a backhaul connection, forexample. The eNBs 110 can also communicate with one another, forexample, directly or indirectly via wireless or wireline backhaulcommunication networks. As described herein, functions described asbeing performed by the eNB 110 can be performed, or partly performed bythe controller 130 and vice versa.

In some embodiments, certain of the UEs 120 can move within a respectivecell or may move from cell to cell. For example, the UE 120 c can be ata cell edge 112 a between the cell 102 a and the cell 102 b. A cell edge112 b can lie between the cell 102 b and the cell 102 c. A cell edge 112c can lie between the cell 102 c and another cell 102 not shown in thesystem 100. Not all cell edges 112 are labeled for ease of descriptionand figure clarity. However, as used herein, the cell edges 112 define a“border” or an “overlap area.” between adjacent cells 102. The celledges 112 are areas in which the UEs 120 may be able to receive signalsfrom more than one eNB 110 or experience interfering signals frommultiple eNBs 110. The UEs 120 can be dispersed throughout the cells 102and the system 100, and each of the UEs 120 can be stationary or mobile.

Various interference mitigation methods can be implemented in order tominimize, for example, the interference the UEs 120 experience at thecell edge 112 a. In some examples, 4G LTE Advanced interferencemitigation techniques, such as, for example, coordinated multipoint(CoMP) systems can be used to send and receive data to and from a UEcoordinated by several points to ensure the optimum performance isachieved even at cell edges. CoMP can include a range of differenttechniques that enable the dynamic coordination of transmission andreception between adjacent cells of different base stations or adjacentsectors of the same BS over a variety of different base stations. Theaim is to improve overall quality for the user regardless of theirposition relative to the cell edges 112 as well as improving theutilization of the network while sharing the same spectrum band. CoMPcan turn the inter-cell interference (101) into a useful signal,especially at the cell edges 112 where wireless performance may bedegraded.

In some embodiments, CoMP can be conducted between cells 102. Forexample, as the UE 120 c approaches the cell edge 112 a of the cell 102a as it moves to the cell 102 b, the eNB 110 a and the eNB 110 b canconduct inter-site CoMP. There can be increased interference near thecell edges, so CoMP provides a manner in which the UEs 120 canexperience reduced interference, even at the cell edge. Interferencemitigation between adjacent cells 102 can also be accomplished throughCell Reference Signal (CRS) Muting and Single Frequency Networks (SFN).These methods are described in more detail below.

FIG. 2 is a graphical representation of an embodiment of the system ofFIG. 1 using directional antennas. A cell 200 can represent one or moreof the cells 102 of FIG. 1 served by an eNB 210 having directionalantennas. Each of the directional antennas can have an associated RRU,providing three RRUs for the cell 200, These three RRUs are collocatedat the center of cell 200 where each provides coverage to cells 202 a,202 b and 202 c respectively.

Using the eNB 210, the cellular map of the system 100 (FIG. 1) can beredrawn with the eNBs 110 located at the points where each of thehexagons describing the coverage areas 104 converge. This is depicted inFIG. 2 and results in three sectors 202 ascribed to the cell 200. Thusthe cell 200 can be described in terms of the three sectors 202 a, 202b, 202 c, each represented as a hexagon.

The eNB 210 can have three directional antennas aimed in three differentdirections with, for example, 120 degrees associated with each of thethree sectors 202 (S1 202 a, S2 202 b, S3 202 c) within the cell 200(totaling 360 degrees). The eNB 210 can then receive and transmit intothe three different sectors at different frequencies, for example. Forexample, a frequency reuse of n=1 provides the same frequency or channelfor use in each sector. A frequency reuse factor of n=3 can providethree non-interfering channels (one in each sector) for use by the UE120, for example. This is described below in connection with FIG. 3. Insome embodiments, the eNB 210 can have three directional antennae eachwith approximately 120 degrees of coverage. Thus each antenna of thethree antennas can be designated to provide service to one of thesectors S1, S2, and S3.

FIG. 3 is a graphical representation of an embodiment of a system usingfrequency reuse factors according to the system of FIG. 2. The cell 200and the three sectors (S1, S2, S3) of FIG. 2 can have differentfrequency reuse factors. In some embodiments, the frequency reuse can beset to three, or n=3, where n is the frequency reuse factor within thesystem. In such scenario, cell 200 would use three different frequencybands, one for each of sectors S1, S2, and S3. Using three differencefrequency bands for the three sectors can minimize or eliminateinterference between these sectors at the sector edges. However this cancome with an additional cost over using a single frequency band, byhaving to procure more spectrum, or radiofrequency (RF) bandwidth, forthe additional channels/bands. The numbers A1, A2, A3 in FIG. 3 arerepresentative of channel numbers, and can repeat every 3 cells, asshown. In some examples, large cells can be subdivided into smallercells for high volume congested areas as shown in sector 310. The sector310 can have smaller subdivisions served by, for example, pico cells orfemto cells.

In some embodiments, a frequency reuse of one (1) can also beimplemented the system shown in FIG. 3. With frequency reuse of 1, allthree sectors (S1, S2, S3) of the eNBs 210 share the same spectrum band.By using the same spectrum band in each sector, wider spectrum bands canbe achieved, thereby maximizing the amount of bandwidth used in eachsector. However, a frequency reuse factor of one (n=1) introducesinterference from sector to sector and from cell to cell. As shown inFIG. 2 for example, the sector 202 a and the sector 202 b are adjacent,and can overlap, at a sector edge 212 a. The sector 202 b and the sector202 c can overlap at a sector edge 212 c. Similarly, the sector 202 cand the sector 202 a overlap at a sector edge 212 b. The sector edges212 a, 212 b, 212 c may be referred to collectively as sector edges 212.Certain interference mitigation techniques, such as, for example, CoMP,CSR-muting, and SFN can address interference at the sector edges 212.

In some other embodiments, the frequency reuse factor can be adjusted tomitigate inter-sector interference. For example, by assigning differentfrequency bands to each of the sectors A1, A2, A3, in FIG. 3,sector-to-sector interference can be mitigated. With frequency reuse ofn=3, these three channels A1, A2, A3 can represent three differentchannels or frequency bands in use for wireless communication within thecells 200.

In some examples, telecommunications providers can deploy voice and datacellular networks over wide inhabited areas. This can allow mobilephones and mobile computing devices to be connected to the publicswitched telephone network (PSTN) and public Internet. However, as moreusers consume more data, these networks can become more congested.Nevertheless, a 3-sector configuration of base station (e.g., the eNB210) antennas can remain, even in new cellular network designs andlayouts. In some examples, the three-sided antenna mounting on cellulartowers can limit the ability to change from three-sector deployment tomulti-sector deployment without using dual bean antennas.

When additional capacity is needed in congested networks, service areascan be further subdivided as shown in the sector 310. Cell divisionthrough use of smaller cells can add additional capacity, but it canalso come with the cost of new site acquisition, including the need toprovision power and backhaul for the new sites. This has certaindrawbacks, such as additional capital expense. More sites can also meanmore operating expenses for site rental, power, backhaul, andmaintenance.

Therefore, it may be desirable to add more sectors to an existing site,in order to enhance the tonnage delivering capacity of a site, withoutincurring the cost of new site (or additional spectrum bandwidth)acquisition.

In some embodiments, each of the sectors S1, S2, S3 of FIG. 2 can usethe same frequencies and bandwidth (e.g., n=1) to provide services intheir individual sectors. In 4G LTE, for example, each of the sectorsS1, S2, and S3 (FIG. 2) can individually use a 20 MHz bandwidth, andassuming an average spectral efficiency of 3.0 bps/Hz, each sector canhave a throughput of approximately 60 megabits per second (Mbps) bitratewith a 27 gigabyte (GB) tonnage delivering capacity per hour.Accordingly, the cell 200 can have an average throughput of 60 megabitsper second in each sector, and an aggregate throughput of 3×60 Mbps anda site tonnage of 3×27=81 GB per hour. In some embodiments, it ispossible to further subdivide the three sector coverage into moresectors (e.g., 4, 5, 6, etc. sectors), each sector having the same orsimilar capacity. Adding additional sectors to the cell 200 canproportionally increase the tonnage delivering capacity of the cell 200.Additional sectors can be added by using dual beam and multi beamantennas. This is described below in connection with FIG. 4.

Similar to the system 100, the cell 200 that is subdivided into multiplesectors can conduct intra-site CoMP as the UEs 120 move from sector tosector to mitigate interference at the sector edges 212. This can alsobe referred to herein as inter-sector CoMP. This can allow the eNB 210of the cell 200) to provide uninterrupted service to multiple UEs 220,even at the sector edges 212.

CoMP may have a plurality of transmission modes, e.g., Joint Processing(JP) mode, dynamic point selection (DPS), joint reception, CoordinatedScheduling/Beamforming (CS/CB) mode, etc. In JP mode, the downlink datafor a mobile device (e.g., the UE 120) may be transmitted from severallocations simultaneously (Joint Transmission). A simpler alternative isDPS, in which data is available at several locations (e.g. eNB 210), butthe data is generally sent from one location at any one time. In CS/CBmode, the downlink data from the eNB 210 to the UE 120 for a mobiledevice is typically available and transmitted from one point (e.g. eNB210). The scheduling and optional beamforming decisions are generallymade among all cells (e.g., the cells 102) in the CoMP set. Locationsfrom which the transmission is performed can be changed semi-statically.

CoMP may generally have four different deployment scenarios. Using thesystem 100 of FIG. 1 as an example, the first deployment scenarios canbe: homogeneous network intra-eNB CoMP (Scenario 1); homogeneousinter-eNB CoMP (Scenario 2); heterogeneous network in which eNBs areconfigured with different PCIs (Scenario 3); and heterogeneous networkin which eNBs are configured with the same PCI (Scenario 4). Scenario 1and Scenario 2 are both for homogeneous networks, and differ in whetheroptical fiber is deployed between physical nodes for backchannelcommunications. In Scenario 2, the optical fiber permits an eNB tooperate remote radio units (RRU) for CoMP over a larger area. Scenario 3and Scenario 4 are both for heterogeneous networks but also differ inthat, in Scenario 4, low power transmitters in the area of a macro cellare allowed to share a same physical cell identity as the macro cell.

FIG. 4 is a graphical representation of an embodiment the cell of FIG. 2using dual beam antennas. A cell 400 can be served by an eNB 410. Thecell 400 can be divided into six sectors 402. The sectors 402 arelabeled as 402 a, 402 b, 402 c, 402 d, 402 e, 402 f.

In some embodiments, the eNB 410 can be similar to the eNB 210, wherethe individual single beam directional antennas of the eNB 210 arereplaced with dual-beam directional antennae resulting in the sixsectors 402. In some embodiments, this six sector arrangement can beaccomplished by implementing dual beam antennas in each of the threesectors 202 of FIG. 2. Each existing single beam antenna can bereplaced, one-for-one with a new dual beam antenna. The sector 202 a S1of the cell 200 can be split using a dual beam antenna to arrive atsectors S5 and S6 of the cell 400. Similarly, the sector S2 of the cell200 split into sectors S1 and S2 of the cell 400, and the sector S3 ofthe cell 200 can be split into the sectors S3 and S4 of the cell 400,each using dual beam antennas. Accordingly, the cell 400 can preserve acell arrangement using three antennas of the cell 200, with two beamsper antenna and one sector per beam (e.g., the cell 400).

This arrangement can provide six individual beams corresponding to thesix sectors 402. Each beam can then have approximately 60 degrees ofcoverage per each of the sectors 402. For ease of description, the cell400 is represented as a circle instead of the three hexagonal sectors asin FIG. 2. The same is true for the following figures.

In some embodiments, each of the sectors 402 (S1, S2, S3, S4, S5, andS6) of the eNB 410 can use the same frequencies and bandwidth. Thisresults in a frequency reuse of n=1. Similar to above, each of thesectors S1-S6 can have a capacity of approximately 60 megabits persecond (Mbps) bitrate with a 27 gigabyte (GB) tonnage deliveringcapacity per hour. Since the cell 400 has six sectors, the entire cell400 can support 6×60 Mbps and a site tonnage of 162 GB.

In some embodiments, such an arrangement can implement CoMP betweenadjacent sectors (e.g., the sectors S1-S6) using dual- or multi-beamantennas to achieve large capacity increases. In some embodiments, useof multi-beam antenna can increase capacity by 100%-500%. Dual beamantennae can be used as a primary example herein but differentconfigurations such as three, four, five, or six (or more) beam antennasare also contemplated.

Some embodiments can deploy poly beam antennas and initially connectthem to the same RRU sector. As capacity needs dictate, additionalremote radio units (RRU) and base band units (BBU) can be added toincrease capacity.

Some embodiments can deploy poly beam antennas and connect the beamsusing frequency reuse of two (n=2). In this arrangement, each antennabeam is connected to an alternate frequency channel in order toeliminate interference to adjacent beams.

In some other embodiments, the use of CoMP can be adapted for use inmulti-sector systems. Instead of using CoMP solely for inter-site cellassignment (e.g., from one cell 102 a to the next cell 102 b, 102 c),intra-site CoMP (or inter-sector CoMP) can be implemented to handlesituations where the UEs 120 are near a sector edge (e.g., the sectoredges 412) within the cell 400. These UEs 120 near the sector edges 412can also be referred to as sector edge UEs. In a similar manner, the UEs120 near the edge of the cell 400 can be referred to as cell edge UEs.The cell edge UEs can also be sector edge UEs being located at, forexample, a maximum range from the eNB 410 serving the cell 400 and nearan adjacent cell 400.

The cell 200 (e.g., a base station or eNB 210) of FIG. 2 with the threesector configuration shown has three sector edges 212 dividing thesectors S1, S2, and S3. The UEs 120 located at the center of the sectors202 may enjoy strong signal and low or no interference from adjacentsectors 202. The UEs 120 close to one of the sector edges 212 canexperience inter-sector interference due to the use of the same spectrumchannels (e.g., n=1) on all three sectors.

When the six sector configuration of the cell 400 is considered, thenumber of sector edges 412 increases from three to six. As the number ofsectors per site is increased past from 3, to six, to 9, 12, 15, etc.,the number of sector edges where a UE 120 experiences interference fromtwo adjacent sectors also increases. As the number of sectors isincreased, antennas with multiple narrower beams can be implemented asin the cell 400. Narrow beams can have sharper side lobes than widerbeams (see, FIG. 5). For example, a three sector antenna configurationwith 120 degree-wide beams can have a large area of overlap at thesector edges 212. A properly designed six sector antenna configurationwith 60 degree coverage areas (e.g., beams) per sector can have a muchsmaller area of overlap at the sector edges 412 (see, FIG. 6). This candecrease inter sector interference. Consequently the number of UEs 120in the overlap area of interference can increase as the number ofsectors per cell is increased. Therefore coordination between twoadjacent sectors is necessary to reduce or eliminate inter-sectorinterference. Inter-sector interference can be a predominant form ofinterference in base stations using frequency re-use factor equal to one(n=1).

Inter-sector coordination methods can be used to reduce interference atthe sector edge or the cell edge. Such techniques can rely on receivedsignal strength information (RSSI) at the UE 120. The UE 120 can alsogather Reference Signal Receive Quality (RSRQ) and report it to theserving sector (e.g., the eNB 410). Such measurement information can beincluded in a measurement report to the eNB 410. As the number ofsectors is increased from three to six, to 9, to 12, 10, 15, etc., agiven UE 120 can experience acceptable RSRQ from multiple sectors (ofadjacent eNBs 110, for example). Using RSRQ as a way to distinguish themost appropriate or optimum serving sector may be advantageous. Theserving sector in this sense can be one of the sectors 402 (e.g., withinthe cell 400) that provides services to the UE 120. Similarly, theserving eNB can be, for example, the eNB 410 serving the UE 120 withinthe cell 400 and/or the sectors 402 d, 402 e. Using the RSRQinformation, the eNB 410, for example, can calculate and determine whichUE 120 should be assigned to which sector 402 in order to provide anoptimal signal and service. The UE 120 can also independently determinewhich sector (e.g., the sectors 402) should be the serving sector. Insome embodiments, a GPS location can also be used to supplement the RSRQmeasurements, for example. Using the example of FIG. 4, the eNB 410 candetermine which of the sector 402 d and the sector 402 e should be theserving sector based on measurement reports having signal measurementinformation or location data.

The eNB 210 (FIG. 2) using three sectors per site, for example, canutilize a unique PCI in each sector 202. Therefore, the ReferenceSignals (RS) broadcast from the eNB 210 in each sector can causeinterference in its neighboring sectors 202. This can particularly be anissue in the sector edge 212 area where the UE 120 can receivesufficiently strong reference signals from two adjacent sectors 202 ofthe same BS (e.g., the eNB 210).

Cell Reference Signal (CRS) interference has been identified as apredominant cause of performance degradation at the sector edges 212even when there is relatively low traffic on an interfering neighboringsector 202. As noted above, when dual beam antennas are used to replacesingle beam antennas in order to increase site capacity (see FIG. 4) innetworks with frequency reuse of n=1, the number of sector edges 212experiencing inter-sector interference also increases. In order tomitigate CRS interference at the sector edges 412, two additionalmethods can be implemented in combination with dual beam antennas toreduce or eliminate CRS interference.

The first method includes combining dual beam antenna with the use ofCRS Muting techniques. CRS Muting can selectively mute, or refrain fromtransmitting, an RS signal in LTE Resource Blocks (RB's) that are idle.There is a minimum quantity of RS signals that are necessary in order toallow UEs to establish synchronization, but it is not necessary totransmit a RS signal in every single RB particularly when no userinformation is being transmitted in a given RB. By selectively mutingthe RS in the majority of idle RBs, CRS interference is diminished andin some cases, eliminated. Furthermore, coordinating the idle RB's of aneighboring sector with user RB's of a serving sector used to serve celledge users further improves RB utilization of the neighboring sector.This way, only idle RB's which were not being used to transmit userinformation in the neighboring cell, are used to coordinate with theserving cell RB's used for cell edge UEs. This coordination allows forefficient utilization of RB's in the neighboring cell. User informationis information that is not signaling information, such as RS and caninclude data transferred between the UE and eNB on the uplink and eNBand the UE on the downlink.

In some embodiments, CRS Muting can be combined with downlink CoMP. Sucha combination can not only eliminate CRS interference, but also benefitfrom coordinated transmission of the same user information from twoadjacent sectors 412. This can allow the eNB 410 to serve a strongersignal to the UEs (e.g., the UE 120) at the sector edges 412. Usingthese interference reduction methods, the UEs 120 at the sector edges412 may receive the highest level of modulation and bit rate, enablingprovision of uniformly high bit rates to all of the UEs 120 in the cell400, independent of their location relative to a cell edges or thesector edges 412.

By creating a six sector configuration from a three sector configurationusing dual beam antennas, the cell 400 can increase the total number ofRB's available in all six sectors, and thereby increase capacitydelivered by the three additional sectors 402 (over the cell 200). Thiscomes at the minor expense of shared RB utilization by some UEs 120 atthe sector edges 412 however; this can increase the modulation andthereby spectral efficiency of RBs. Since not all of the sectors 402 arenecessarily fully loaded all the time, the shared RB utilization can bescheduled with idle blocks of neighboring sectors 402 and minimize theimpact of RB sharing.

The second method can include combining the dual beam antennas with theuse of SFN. With SFN, the PCI of all sectors 402 within the cell 400 canshare the same code. Therefore all reference signals may be synchronizeddue to constructive interference experienced by the UE 120 located at,for example, the sector edge 412 d. By synchronizing the CRS of all ofthe sectors 402 of eNB 410, for example, CRS interference is eliminatedbetween the sectors 402. Coordination at the eNB 410 can then ensurethat the UEs 120 located at the sector edges 412 can be served withreference signals from both neighboring sectors 402 of the cell 400 andrely on RF combining to deliver the strongest reference signal possiblewith no self-interference to the UEs 120 at the sector edges 412. UEs120 at the center of one of the sectors 402 may be served by a singleserving cell (e.g., the eNB 410), since antenna separation ensureslittle to no interference for the UEs 120 located at the center of thesector 402.

In some embodiments, SFN can be combined with downlink CoMP. Such acombination can not only eliminate CRS interference, but also benefitfrom coordinated transmission of the same user information from twoadjacent sectors 412. This can allow the eNB 410 to serve a strongeruser signal to the UEs (e.g., the UE 120) at the sector edges 412. Usingthese interference reduction methods, the UEs 120 at the sector edges412 may receive the highest level of modulation and bit rate, enablingprovision of uniformly high bit rates to all of the UEs 120 in the cell400, independent of their location relative to a cell edges or thesector edges 412.

This method shares RB resources for UEs 120 that are at the sector edges412. However because the dual beam antenna configuration doubles thetotal amount of RB's at a cell site (e.g., the cell 400), the tradeoffbetween sharing a small portion of RBs and delivery of higher throughputto UEs 120 at the sector edges 412 is well justified.

In another embodiment, frequency reuse factors can also be adjusted tomitigate inter-sector interference. For example, the cell 400 having thesix sectors 402 can use a frequency reuse of, for example, n=2. In thecell 200, n=2 may not be practical given the odd number of sectors 202.That is, as shown in FIG. 3, distribution of only channels A1 and A2throughout the diagram would results in a difficult situation forinterference mitigation without another system such as CoMP. Frequencyreuse of n=2 in an even-numbered sector cell (e.g., the cell 400) mayeliminate inter sector interference by itself, without the need foranother interference mitigation technique, such as CoMP.

In the cell 400 having an even number of sectors 402, frequency reusen=2 is possible by alternating two different channels (e.g., A1 and A2)in adjacent sectors 402. This virtually eliminates the need forinter-sector or inter-cell interference mitigation as the adjacentchannels are different. Such an arrangement can maximize the throughputof each sector, thereby increasing cell site throughput while allowingall UEs 120 to receive higher modulation and bitrate.

Frequency reuse of n=2 can further be done by splitting existingfrequency bands, for example, in half. For example, if a 20 MHz band isassigned for a given cell, 10 MHz can be used for alternating sectors tominimize inter sector interference in the six sector cell 400.

FIG. 5 is a plot diagram of antenna coverage in the embodiment of FIG.2. A plot 500 depicts the three sectors (e.g., the sectors S1, S2, andS3) of the cell 200, for example. The individual antenna coverages areshown overlapped to provide antenna coverage to 360 degrees of the cell300. In the plot 500, each of three beams 504 (dotted line), 506 (solidline), 508 (dashed line) has a respective overlap 502 with an adjacentbeam. The overlaps are labeled 502 a, 502 b, 502 c. For example, thebeam 504 has the overlap 502 a of approximately 60 degrees with the beam506. The amount of the overlap 502 a is shown by two bold dashed lines.The beams 506 and 508 have similar overlaps 502 b, 502 c. The dashedlines represent an approximation of the overlap 502 a and may be largeror smaller than 60 degrees as shown.

The overlaps 502 present some cellular coordination issues whereinterference between adjacent sectors is concerned. When the UE 120(FIG. 1) is located in one of the overlaps 502, the eNB (e.g., the eNB410) associated with the beams 504, 506, 508 can use some kind ofinterference mitigation in order to reduce interference and improve thequality of the signal presented to the UE 120. A larger overlap 502 canresult in a requirement for additional coordination between theoverlapping sectors. The additional coordination can also result inincreased in shared RB utilization and overhead that can lower overallsystem throughput.

FIG. 6 is a plot diagram of antenna coverage in the embodiment of FIG.4. A plot 600 is similar to the plot 500 with the six sectors (e.g., thesectors S1, S2, S3, S4, S5, and S6 of the cell 400) overlapped toprovide antenna coverage to 360 degrees of the cell 400. The cell 400uses a similar three sector division as the three sector cell 200,however the cell 400 can implement dual beam antennas in each of threesectors (e.g., the sectors 202). Each of the dual beam antennas canprovide services to a 60 degree sector of the cell (e.g., the cell 400),providing a total of six sectors S1-S6 as shown corresponding to arespective beam 604, 605, 606, 607, 608, 609.

The plot 600 shows overlaps 602. The overlaps 602 lie between each ofthe adjacent beams 604-609. However, when compared to the overlaps 502of FIG. 5, the overlaps 602 are significantly smaller. This can be aresult of the narrower beam patterns of the dual-beam directionalantennas. As shown in the plot 600, the overlaps 602 are less thanapproximately 15 degrees each, at their widest points. Accordingly, thebeams 604-609 may be tighter, narrower, and/or more focused than thebeams 504, 506, 508 of the single beam directional antennas of FIG. 5.As a result, there is a smaller overlapped areas between the sectors 402(FIG. 4) and thus a smaller area in which the serving cell may need toconduct interference mitigation between each of the adjacent overlappingareas of the six sectors.

FIG. 7 is a graphical representation of a four sector cell. A foursector cell 700 can have an eNB 710 that serves four sectors 702. Thesectors 702 are labeled sectors 702 a, 702 b, 702 c, 702 d. Each of thesectors 702 can have a sector edge 712, similar to the sector edges 212and the sector edges 412 of previous embodiments. The arrangement of thefour sector cell 700 can be similar in layout and employment as thethree sector cell 200.

Similar to the cell 200 and the cell 400, the cell 700 also may alsoconduct some kind of interference mitigation at the sector edges 712 andcell edges, for example. In one embodiment, the cell 700 can change afrequency reuse factor. Using frequency reuse of n=1 can require thatthe eNB 710 conduct CoMP, RCS muting, SFN or some other reactiveinterference mitigation, as the sectors 702 are all using the samefrequency band, A1, for example. Given that there are an even number ofsectors 702, a frequency reuse of n=2 can also be used. For example, ifA1 and A2 are the frequency bands in use, then the two bands can bealternated. A1 can be in the sector 702 a and 702 c, while Band A2 canbe used in the sector 702 b and the sector 702 d. Thus, at the celledges 712, no further interference mitigation is required. In theembodiment using n>1 where adjacent sectors 702 are not utilizing thesame channels, additional interference mitigation using CoMP, CRSmuting, and SFN may not be required.

FIG. 8 is a graphical representation of an embodiment of the cell ofFIG. 7 using dual beam directional antennas. A base station, 810, canserve a cell 800. The cell 800 can be, for example, the cell 700 withthe single beam directional antennas, replaced with dual beamdirectional antennas. The cell 800 can thus have eight sectors 802,labeled 802 a, 802 b, 802 c, 802 d, 802 e, 802 f, 802 g, 802 h.Similarly, the sectors 802 have corresponding sector edges 812 a-812 h.The cell 800 can therefore be similar to the cell 400 incorporating adual beam directional antenna in place of a single beam antenna in afour sector arrangement. The dashed lines of a portion of the sectoredges 812 represent a subdivision of the four sector arrangement of thecell 700 to eight sectors 802. As a result, the cell 800 has an evennumber of sectors 802, thus the frequency reuse factor of n=2 ispossible.

Replacing single beam antennas with dual beam antennas to create theeight sector arrangement (the sectors 802) from the four sectors 702results in twice as many sector edges and twice as much interference.Frequency reuse of n=2 can eliminate the inter sector interference inthe sectors 802.

The cell 800 can differ from the cell 400 in the angular coverage ofeach individual sector 802. For example, the sector 402 a (FIG. 4) canhave a 30 degree coverage, while the sector 802 a has a 45 degreecoverage.

FIG. 9 is a graphical representation of a coverage area of anotherembodiment of the cell of FIG. 2. A cell 900 can have four sectors S1,S2, S3, S4, similar to the cell 700, but with different angularcoverages. For example, the cell 900 can be the cell 200 with only onesector modified to form the sectors 902 a, 902 b using the dual beamantenna. This can be done, for example, in response to usage rates ofthe eNB 210 or congestion in the sector 202 a. The sector 202 b of FIG.2 can be replaced with a dual beam antenna to form sectors 902 a and 902b. This can subdivide the sector 202 b, providing two approximately 60degree sectors 902 a, 902 b (S1, S2 of FIG. 9) and two 120 degreesectors 902 c, 902 d (S3, S4 of FIG. 9). This can also be referred to asan improved antenna array.

In some embodiments this can provide a number of advantages. As notedpreviously, any time the number of sectors in a cell increases with theimplementation of a dual beam directional antenna to replace, forexample, a single beam antenna, the number of sector edges (e.g., thesector edges 412, 812) increases. In the n=1 configuration of the cell200, for example, this may necessitate the use of CoMP, CRS muting orSFN for interference mitigation. However, with the formation of thesector 902 a and the sector 902 b, four sectors 902 are formed, allowingthe use of frequency reuse factor n=2. Thus, two channels (e.g., A1, A2)can be used in an alternating manner, assigning for example, A1 to S1and S3 and A2 to S2 and S4 of the cell 900.

FIG. 10 is a graphical representation of a coverage area of anotherembodiment of the cell of FIG. 9. A similar approach can be taken withthe sector 902 c as was taken with the sector 202 b above. The singlebeam directional antenna serving the sector 902 c can be replaced with adual beam antenna to form sectors 922 a, 922 b. The cell 900 can be thusbe modified into a cell 950 subdividing the sector 902 c providing fourapproximately 60 degree sectors (S1, S2, S3, S4) and one 120 sector(S5). Accordingly, virtually any number of subdivisions can beimplemented. In the examples of FIG. 9 and FIG. 10, it can be seen thatdifferent antenna sector configurations can be useful for differentapplications, such as when there is an irregular distribution of UEs 120in a given sector 202.

FIG. 11 is a graphical depiction of another embodiment of the cell ofFIG. 4. The cell 400 is shown with the eNB 410. A plurality of UEs 120are distributed among the six sectors of the cell 400. For ease ofdescription, not all of the UEs 120 are labeled.

As described in connection with the foregoing figures, increased sectornumbers increases the presence of inter-sector interference,particularly at the sector edges 412. The eNB 410 can implement certainkinds of interference mitigation methods in order to reduce or eliminatesuch interference.

In intra site CoMP, the eNB 410 can assign individual UEs 120 to a givensector among the six available sectors. In some embodiments, the eNB 410can transmit a reference signal in each sector 402 such as the PCI or RSdescribed above. The UEs 120 can receive the reference signals andreport to the eNB 410 a receive signal strength indication (RSSI) orreceived signal to noise ratio (RSNR). The RSSI or the RSNR can be afactor that the eNB 410 analyzes in order to assign the UEs 120 torespective sectors 402 within the cell 400.

In some embodiments, the eNB 410 can further use geographic position tosupplement the intra site CoMP and coordinate sector assignment to eachof the UEs 120. In some examples, the eNB 110 is stationary, so it canhave a fixed geographic position. Similarly, each of the dual bandantennas used by the eNB 410 can have a fixed coverage area. Thereforeif the eNB 410 knows the approximate position of an individual UE 120,the eNB 410 can assign the UE 120 to a particular sector.

In an embodiment, the eNB 410 can triangulate a position of a UE 120 f.In such an embodiment, the reports of RSSI or RSNR received at one ormore antennas of the eNB 410 can be used to approximate the position ofthe UE 120 f. In another embodiment, the UE 120 f can triangulate itsown position using a received signal from the eNB 410 (e.g., the pilotsignal of the sector 402 c) or another eNB from an adjacent cell. Inanother embodiment, the UE 120 f can also report a global positioningsystem (GPS) position. Such position information can improve UE sectorassignment in intra site CoMP or inter sector Co M P.

In another embodiment, the UE 120 g may be on the sector edge 412 dbetween the sector 402 d S4 and the sector 402 e S5, as shown. In suchan embodiment, the eNB 410 can receive an indication of signal strengthfrom the UE 120 g from the antenna beams serving S4 and S5. In the eventthat the RSSIs are ostensibly equal, the eNB 410 can coordinate sectorassignment based on, for example, direction of motion of the UE 120 g,or a geographic position of the UE 120 g. The eNB 410 can also, forexample, assign the UE 120 g to the sector with higher availablecapacity or lowest population all other aspects being equal.

In some embodiments, the UEs 120 can be stationary or slow moving. Thiscan decrease or minimize the amount of CoMP processing required forstationary or slow moving UEs 120. Conversely, for fast moving UEs 120,more CoMP processing may be required, particularly when additionalsectors (e.g., six sectors or more) are present.

When the eNB 210 (e.g., a base station) is serving fixed wireless users(the UEs 120), all of the UEs 120 are stationary, except when they arecommissioned or decommissioned or when they are moved to be installed inother locations. Once installed, fixed customer premises equipment (CPE)may be stationary by nature. Therefore, using known or fixed GPScoordinates of a fixed UE 120 may be a practical way of assigning fixedUEs 120 to their serving eNodeB 110 sectors. Such fixed or stationaryCPE can also conduct measurement of RSRQ, or RSSI, for example todetermine the best serving sector 402.

When the eNB 410 is serving semi-fixed users, such as nomadic UEs 120that move infrequently, (such as a few times a day), then the GPSlocations can be updated frequently enough so that the optimal sectorcan be determined based on the sector assignment (FIG. 13). In asemi-static environment, the eNB 410 can gather GPS information byrequesting it from the UEs 120 to report a change in their GPScoordinates compared to the last one reported. In some embodiments, theGPS coordinates can be requested to make sure the UEs 120 have not movedor to accommodate UEs 120 that have moved.

Some mobile networks can support slow moving UEs 120 (e.g., less than ameter per second). For example, a stadium full of thousands of peoplecarrying mobile devices looks like a semi-static environment from thepoint of view of how quickly users move.

In a fully mobile network where the UEs 120 are on high speedtransportation vehicles, such as cars, buses, and trains, the dynamicmethod of updating signal measurements or GPS locations may be needed.These networks must also support handovers whereby the serving basestation hands over a moving UE 120 to the next serving cell or servingsector. It is possible to use information from the existing means ofhandover, along with GPS locations to determine which sector edge agiven UE is approaching and crossing and for that duration, use CoMPtechniques to enhance the signal strength delivered to this UE.

In another embodiment, the eNB 410 can further use frequency reusefactor n=2, for example. This can virtually eliminate the need forinterference mitigation techniques, such as CoMP at the sector edges412, as the frequency reuse n=2 provides for different channel, A1, A2for instance, in adjacent sectors 402.

FIG. 12 is a flowchart of an embodiment of a method for intra sitecoordinated multi point communications. A method 1200 is an embodimentof “Enhanced CoMP” allowing the gathering of measurement reports (MR)from each UE 120 in order to allow assignment of UEs 120 to a givensector. The method 1200 can allow the eNB 410 to assign UEs 120 in thecell (e.g., the cell 400, 800, 900) to a given sector (e.g., the sectorsS1-S6 of FIG. 4, FIG. 11) based on the MR from each individual UE 120.The method 1200 is described below in connection with a three sector eNBsuch as the eNB 210; however any number of sectors can be implemented.Similar descriptions are also used below in connection with FIG. 13. theeNB 410 (e.g., a base station, or the eNB 410) can have n-tables, wheren is the number of sectors served by the cell (e.g., the cell 400). Themethod 1200 is described in connection with the cell 400 (FIG. 4),however the method 1200 is applicable to any of the cells describedherein

The method 1200 can allow an eNB 410 to scan the UEs 120, for example,one or more sector at a time to gather the measurement report (MR) fromthe UEs 120. The measurement report can include the RSRQ information.The measurement report can also include position information (e.g., GPScoordinates) of each of the UEs 120. Information can be gathered fromeach sector until all sectors have gathered their table of UEs 120 alongwith their corresponding GPS locations and RSRQ information.

At block 1210, a serving cell (e.g., the eNB 410) of a given sector(e.g., the sector 202 a) can send a reference signal (RS) to the antennabeam associated with, for example, sector S1.

At block 1220, all of the other sectors of the serving cell (eNB 410)can be muted, and all UEs 120 in the sector, at the sector edges (e.g.,the sector edges 412) or within range of the eNB 410 can listen andreceive a reference signal from the antenna serving sector S1. Based onthe location of the UE 120 relative to the coverage area of the sectorS1 antenna beam, each UE 120 that receives the RS can generate ameasurement report (MR). The measurement report can include RSRQinformation. The MR can further include a GPS position of the UE 120.The GPS position or coordinates can be known through one of many ways,such as having a GPS receiver in the UE 120 or through radio frequencytriangulation of the PCI or RS, for example. The process of block 1220can occur simultaneously with the process of block 1210.

The eNB 410 can request reports from each of the UEs 120 present in thecoverage area. At block 1240, each UE 120 can transmit a respective MRto the serving eNB (e.g., the eNB 210, 410). The UEs 120 can send theirrespective MR's to the serving cell sequentially.

At block 1250, the serving cell (e.g., the eNB 210, 410) can compile theMRs recording and record a position of each reporting UE 120. Theposition can be determined based on triangulation of a RS. The positioncan be determined based on the GPS position of the UE 120. At block1250, the serving cell can then calculate a relative location of each UE120 to its antenna beam (for, e.g., sector S1). Since the serving cellknows its own GPS location and the radiating pattern of each of itsantenna beams, the serving cell can classify each UE 120 as beinglocated at the center of its beam, a right edge of its beam, or a leftedge of its beam. This tabulation of UEs 120 based on relative locationunder the coverage area of an antenna beam (of, e.g., the sector S1),together with the RSRQ information can allow assignment of a value orscore to each UE 120 relative to a specific beam (e.g., the beams forsectors S1, S2, S3 of the eNB 210), and thereby to a specific eNB (e.g.,the eNB 410). The UEs 120 in the center of an antenna beam with a strongRSRQ can be assigned a high score.

At block 1260, the eNB 410 can increment a sector count (SC) (e.g.,sector S1 to sector S2) and then conduct the same process describedabove for the next serving cell (or sector), for example, the sector S2,S3, Sn, . . . for the eNB 410.

At decision block 1270, the eNB (e.g., the eNB 210, 410) can determineif all serving cells or sectors have completed tabulation. The method1200 can be repeated and completed for each eNB 410 until all sectorsare scanned and all UEs 120 have an assigned score.

At block 1280, the eNB can determine that all serving cells/servingsectors have gathered measurement reports from all UEs 120 and havecalculated their relative scores relative to each UE 120. At block 1280,the eNB can assign each UE 120 in the cell to a serving sector.

FIG. 13 is a flowchart of another embodiment of a method for assigning aUE to a serving sector of an eNB. A method 1300 can assign the UEs 120to a sector (e.g., sectors S1, S2, S3 of eNB 210) based on the MR tablesand scores gathered in the method 1200. In some embodiments, the method1200 focuses on gathering MRs from the UEs 120, one serving cell orsector at a time, and scoring the results relative to each serving cellor sector. The method 1300 can go a step further and process the datacollected by the eNB 410 to allocate the UEs 120 to an optimal servingcell or sector within the coverage area, minimizing inter-sectorinterference.

At block 1310, the eNB 410 (e.g., a base station, or the controller 130)can have n-tables, where n is the number of sectors served by the cell(e.g., the cell 400). The method 1300 is described in connection withthe cell 400 (FIG. 4), however the method 1300 is applicable to any ofthe cells described herein.

At block 1320, the eNB 410 can determine which UEs 120 fall in thecenter of a given sector 402 based on location information. The locationinformation can be, for example, signal strength information measured bythe UE 120. The information can also include a GPS position, similar toabove. The UEs 120 at the center of the sector 402 can be assigned tothat sector. For example, if the only RS received at the UE 120 f (FIG.11) is for the sector 402 c or a GPS position indicates the same, the UE120 f can be assigned to the sector 402 c.

At block 1330, the eNB 410 can also confirm that the RSRQ from thatsector received at the UE 120 f, is optimal or at least within apredetermined or acceptable range.

At block 1340, the eNB 410 can allocate UEs 120 to the sectors 402 orserving cells based on proximity to a cell edge line, or the sectoredges 412.

At block 1350, the eNB 410 can allocate the UE 120 to the right servingcell or sector.

At block 1360, the eNB 410 can allocate the UE 120 to the left servingcell.

At decision block 1370, the eNB 410 can compare the serving sector scoreof a sector edge UE 120 with the score of the same UE 120 from theadjacent serving sector.

At decision block 1375, the eNB 410 can determine if swapping theserving sector for that UE 120 might improve the RSRQ. If no, then thegiven iteration of the method 1300 can end.

If yes, at block 1380, the serving sector assignment to the UE 120 canbe swapped. The method 1300 can be repeated until all UEs 120 have beenassigned to their optimal serving cells.

The eNB 410 can then confirm that the RSRQ for the adjacent sector tothe left and right of the assigned sector are lower than a prescribedthreshold. If the signal from adjacent sectors is weak, then theinterference from the adjacent sector signals will also be weak.Therefore, the eNB 410 can transmit to a UE 120 in the center of asector 402 without coordination with the R or L sectors.

For the UEs 120 that fall on or close to a sector edge 412, the UE 120can report acceptable RSRQ from both the right and left sectors. The eNB410 can use measurement reports or location information (e.g., GPScoordinates) of the UE 120 on the sector edge 412 and pick the sector402 that should have lower interference. If the RSRQ of this sector 402is optimal, then this sector will be assigned to the UE 120. Thisprocess can continue until all UEs 120 have been assigned to theiroptimal serving sectors 402.

The eNB 410 can generate a table of UEs 120 in each sector. The tablecan have UEs 120 identified in one of three ways: 1) Center UEs 120 thatdo not need coordination; 2) UEs 120 that are close to the Right SectorEdge: these UEs 120 may need coordination with the Right Sector; and 3)UEs 120 that are close to the Left Sector Edge: these UEs 120 will needcoordination with the Left Sector.

In a six sector environment of the cell 400, and based on the sharpnessof the antenna beam lobes (e.g., FIG. 5, FIG. 6), it is anticipated thatapproximately 80% of the evenly distributed UEs 120 in the cell 400 mayend up in the center of a given sector, with 10% of UEs 120 ending upclose to the right sector edge, and an additional 10% of UEs 120 beinglocated in the left sector edge. This example is based on a function ofthe antenna pattern overlap and the statistical distribution of users.

In this example, coordination can take place on approximately 20% of theUEs 120 served by a given sector. This means that 80% of the UEs 120will not experience notable inter-sector interference. The remaining 20%of the UEs 120 that are located at the edges of a sector may use CoMPtechniques such as selective muting and/or coordinated JointTransmission in order to enhance their signal and eliminateinterference.

FIG. 14 is a functional block diagram of a device for use in the systemof FIG. 1 and the cells of FIG. 4 through FIG. 11 and the methods ofFIG. 12 and FIG. 13. A device 1400 can be used in connection with thesystems and embodiments of the various cells described herein. Forexample, the device 1400 can be implemented in the system 100 (FIG. 1)to perform functions of the eNB 110 and/or the controller 130. Thedevice 1400 can further be used to perform various functions associatedwith the cell 200, the cell 400, the cell 700, the cell 800, the cell900, and the cell 950.

The device 1400 can have a processor 1402. The processor 1402 can beimplemented as one or more processors, processor units, ormicroprocessors. The processor 1402 can also be referred to as a centralprocessing unit (CPU). The processor 1402 can control operation of thedevice 1400. The processor 1402 can implement the steps of the methodsdescribed in the methods of FIG. 12 and FIG. 13 and the functionsassociated with, for example, the controller 130, the eNB 110, the eNB210, the eNB 410, the eNB 710, and the eNB 810. The processor 1402 canperform the various steps within the foregoing flowcharts, in connectionwith the various embodiments of the cells described above, combining,overlapping, repeating, or performing them out of order as needed. Forexample, as noted above, at least the cell 200 and the cell 400 can becombined with elements of the other cells 700, 800, 900, 950.

The device 1400 can also have a memory 1404 coupled to the processor1402. The memory 1404 can include both read-only memory (ROM) and randomaccess memory (RAM). The memory 1404 can provide instructions and datato the processor 1402. At least a portion of the memory 1404 can alsoinclude non-volatile random access memory (NVRAM). The processor 1402can perform logical and arithmetic operations based on programinstructions stored within the memory 1404. The instructions in thememory 1404 can be executable to implement the methods described herein.In some embodiments, the memory 1404 can perform functions associatedwith the method 1200 and the method 1200, in addition to the receipt andstorage of certain measurement reports received from the UEs 120.

The processor 1402 can include or be a component of a processing systemimplemented with one or more processors. The one or more processors canbe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processor 1402 and the memory 1404 can also include machine-readablemedia for storing software. Software shall be construed broadly to meanany type of instructions, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Instructions can include code (e.g., in source code format, binary codeformat, executable code format, or any other suitable format of code).The instructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The device 1400 can also include a transmitter 1406 and/or a receiver1408 to allow transmission and reception of data between the device 1400and a remote location via, for example, a network or directionconnection associated with the UEs 120 and any one of the cells, eNB, orbase stations, etc., described above. The transmitter 1406 and thereceiver 1408 can be combined into a transceiver 1410. The device 1400can also have one or more antennas 1412 a through 1412 n electricallycoupled to the transceiver 1410. The antennas 1412 a-1412 n canrepresent the various antennas in an omnidirectional or directionalconfiguration, in a single-beam, dual-beam, or multi-beam arrangement asdisclosed herein. Each antenna 1412 a-1412 n can be associated with aone or more beams and the various configurations of the sectorsdescribed above. In some embodiments, each beam of the multi-beamantennas can have its own transceiver 1410. The device 1400 can alsoinclude (not shown) multiple transmitters, multiple receivers, multipletransceivers, and/or multiple antennas as needed for variouscommunication standards.

The transmitter 1406 can be configured to wirelessly transmit packetshaving different packet types or functions. For example, the transmitter1406 can be configured to transmit packets of different types generatedby the processor 1402.

The receiver 1408 can be configured to wirelessly receive packets havingdifferent packet types. In some examples, the receiver 1408 can beconfigured to detect a type of a packet used and to process the packetaccordingly.

In some embodiments, the transmitter 1406 and the receiver 1408 can beconfigured to transmit and receive information via other wired orwireline systems or means.

The various components of the device 1400 can be coupled together by abus system 1420. The bus system 1420 can include a data bus, forexample, as well as a power bus, a control signal bus, and a statussignal bus in addition to the data bus. The components of the device1400 can be coupled together or accept or provide inputs to each otherusing some other mechanism.

Those of skill will appreciate that the various illustrative blocksdescribed in connection with the embodiments disclosed herein can beimplemented in various forms. Some blocks have been described abovegenerally in terms of their functionality. How such functionality isimplemented depends upon the design constraints imposed on an overallsystem. Skilled persons can implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the disclosure. In addition, the grouping of functions within ablock or step is for ease of description. Specific functions or stepscan be moved from one block or distributed across to blocks withoutdeparting from the present disclosure.

The various illustrative blocks described in connection with theembodiments disclosed herein can be implemented or performed with ageneral purpose processor, a digital signal processor (DSP), applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, or any combination thereof designedto perform the functions described herein. A general-purpose processorcan be a microprocessor, but in the alternative, the processor can beany processor, controller, microcontroller, or state machine. Aprocessor can also be implemented as a combination of computing devices,for example, a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein can be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module can reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium. An exemplary storage mediumcan be coupled to the processor such that the processor can readinformation from, and write information to, the storage medium. In thealternative, the storage medium can be integral to the processor. Theprocessor and the storage medium can reside in an ASIC.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the present disclosure.Various modifications to these embodiments will be readily apparent tothose skilled in the art, and the generic principles described hereincan be applied to other embodiments without departing from the spirit orscope of the present disclosure. Thus, it is to be understood that thedescription and drawings presented herein represent a presentlypreferred embodiment of the present disclosure and are thereforerepresentative of the subject matter which is broadly contemplated bythe present disclosure. It is further understood that the scope of thepresent disclosure fully encompasses other embodiments that may becomeobvious to those skilled in the art and that the scope of the presentdisclosure is accordingly limited by nothing other than the appendedclaims.

What is claimed is:
 1. A device for wireless communications having acoverage area for providing wireless services to a plurality of userequipments (UEs), the device comprising: a plurality of antennas, eachantenna of the plurality of antennas having two or more beams, theplurality of antennas dividing the coverage area into sectors based onthe two or more beams of each antenna, each sector having an associatedbeam, wherein adjacent beams overlap in an overlap area, the sectorsbeing arranged radially about the device; one or more transceiverscoupled to the plurality of antennas and configured to transmit areference signal in each sector via the associated beam, and receive oneor more measurement reports from the plurality of UEs within eachsector, the one or more measurement reports indicating received qualityof at least one reference signal; and one or more processors incommunication with the one or more transceivers, the one or moreprocessors operable to assign a sector edge UE to a sector based on themeasurement report, the sector edge UE being located at a sector edge ofone or more of the sectors.
 2. The device of claim 1, wherein the one ormore transceivers is further configured to selectively mute at least onereference signal to reduce interference for one or more cell edge UEsserved by adjacent sectors.
 3. The device of claim 2, wherein the one ormore processors are further configured to coordinate the idle resourceblocks (RBs) of a neighboring sector with user RBs of a serving sectorused to serve cell edge UEs.
 4. The device of claim 1, wherein the oneor more processors are further configured to categorize the plurality ofUEs based on the measurement report as one of a cell-center UE and acell-edge UE.
 5. The device of claim 4, wherein the one or moreprocessors are further configured to perform interference mitigation forat least the cell edge UE.
 6. The device of claim 1, wherein theplurality of antennas divide the coverage area into an even number ofsectors and wherein the one or more transceivers implements a frequencyreuse factor of two in the coverage area.
 7. The device of claim 1wherein the reference signal comprises a physical cell identity codethat is identical in each sector, and wherein reference signal of eachsector is synchronized to appear to be generated at the same location.8. The device of claim 1, wherein the one or more transceivers isfurther configured to receive a location report from each UE of theplurality of UEs, the location report including a location of the UEdetermined at the UE.
 9. The device of claim 1, wherein the one or moretransceivers is further configured to receive one or more measurementsreport from each UE of the plurality of UEs, each measurement report ofthe one or more measurement reports indicating a received quality of areference signal.
 10. A method for reducing inter-sector interferencefor a base station having one or more multi-beam antennas each, the oneor more multi-beam antennas having two or more beams and the basestation having a coverage area, the method comprising: dividing thecoverage area into sectors based on one or more beams associated witheach antenna, each beam being associated with a sector, each sectorhaving a sector edge bordering an adjacent sector, the sectors beingarranged radially around the base station; transmitting a referencesignal via each beam to one or more user equipments (UEs) in eachsector, each sector having a reference signal; receiving, at atransceiver coupled to the multi-beam antenna, one or more measurementreports from the plurality of UEs, the one or more measurement reportsindicating receive quality of at least one reference signal; determiningthat at least one UE of the plurality of UEs is a sector edge UE locatedat a sector edge of one or more of the sectors, based on the one or moremeasurement reports; assigning, based on the determining, the sectoredge UE to a sector having a higher receive quality of the at least onereference signal.
 11. The method of claim 10 further comprisingselectively muting at least one reference signal to reduce interferencefor one or more cell edge UEs served by adjacent sectors, the one ormore cell edge UEs being located at a cell edge.
 12. The method of claim11 further comprising coordinating idle resource blocks (RBs) of aneighboring sector with user RBs of a serving sector used to serve celledge UEs.
 13. The method of claim 10 further comprising categorizing theat least one UE based on the one or more measurement reports as one of acell-center UE and a cell-edge UE.
 14. The method of claim 13, furthercomprising performing interference mitigation for at least the cell edgeUE.
 15. The method of claim 10 further comprising dividing the coverageareas into an even number of sectors wherein a frequency reuse factor oftwo is used in the coverage area.
 16. The method of claim 10 furthercomprising transmitting the reference signal comprising a physical cellidentity code that is identical in each sector, wherein reference signalis synchronized in the sectors to appear to be generated at the samelocation.
 17. The method of claim 10, further comprising receiving alocation report from each UE of the plurality of UEs, the locationreport including a location of the UE determined at the U E.
 18. Themethod of claim 10, further comprising receiving more than onemeasurement report from each UE of the plurality of UEs, the measurementreport indicating received quality of a reference signal.
 19. A methodfor improving interference mitigation in a coverage area of a basestation, the coverage area having a plurality of single-beam antennaseach having a form factor, the method comprising; replacing one or moresingle beam antennas of the plurality of single-beam antennas with amulti-beam antenna to form an improved antenna array, the multi-beamantenna having two or more beams and the form factor of the plurality ofsingle beam antennas; dividing the coverage area into sectors based onthe beams of the coverage area after the replacing, each sector beingassociated with a single beam; transmitting a reference signal to one ormore user equipments (UEs) in each sector, each sector having areference signal and a sector edge proximate an adjacent sector;receiving, at a transceiver coupled to the improved antenna array, oneor more measurement reports from a UE of the one or more UEs within eachsector, the one or more measurement reports indicating a receive qualityof the reference signal; determining that the UE is a sector edge UElocated proximate two adjacent sectors based on the measurement report;assigning, based on the determining, the UE to one sector of the twoadjacent sectors having a higher receive quality of the referencesignal.
 20. The method of claim 19, wherein having the same form factorcomprises being housed in a physical package identical to a single beamantenna.
 21. The method of claim 19 further comprising selectivelymuting the reference signal to in at least one sector to reduceinter-sector interference in the adjacent sector.
 22. The method ofclaim 19 further comprising dividing the coverage areas into an evennumber of sectors wherein a frequency reuse factor of two is implementedin the coverage area.
 23. The method of claim 19 further comprisingtransmitting the same reference signal in each sector, wherein referencesignal is synchronized in the sectors to appear to be generated at thesame location.
 24. The method of claim 19, further comprising receivinga location report from each UE of the one or more UEs, the locationreport including a location of each UE determined at each UE.
 25. Themethod of claim 19, wherein the multi-beam antenna comprises two beams.